The color grey has an interesting backstory. There are 50 shades, each with a different percentage of black and white. But, of course, that's basic human knowledge, so let's think outside the box. Cement is grey. Iron ore is considered an important reactant for the production of cement. Natural iron ore is black, and when mixed with other stuff, we get the familiar block of cement, and subsequently, an ugly seal. Meanwhile, elephants are famously grey, except this time, it's not caused by any element. Instead, elephants have melanin, which consists of oligomers and polymers attached in a disorganized fashion.